State wildlife officials are offering a $6,000 reward for information leading to the arrest and conviction of whoever shot and killed an American crocodile.

The body of the 9-foot female reptile known as Blue No. 9 was found floating in Florida Bay on Sunday along the mangroves near Mile Marker 74, said Florida Fish and Wildlife Conservation Commission (FWC) spokesman Bobby Dube.

Islamorada real estate agent Tom Kavney, among those who found Blue No. 9, said she was already bloated.

He said he didn't see any visible wounds but didn't inspect the animal closely.

"I just assume that somebody killed it, because it was a healthy animal," Kavney said.

In late April, the crocodile made news when she laid 27 eggs in a couple's front yard. The spectacle drew plenty of attention in the neighborhood, as well as from wildlife officers and the Monroe County Sheriff's Office.

The FWC waited for Blue No. 9 to lay her eggs in Tollgate Shores near U.S. 1, then removed her from the yard of Elaine and Peter Vlaun.

Wildlife officials working to protect the animals were further stymied when experts determined that none of those eggs would hatch, FWC crocodile response coordinator Lindsey Hord said.

Blue No. 9 was taken to undeveloped bayside waters 4 miles north, to about Mile Marker 77.

Hord said last week's discovery that the eggs were not viable wasn't especially unusual, though he couldn't be sure of the reason. It's possible the eggs were never fertilized by a male, or that Blue No. 9 had a reproductive mishap, he said.

Chemical pollution in the ground has been known to cause problems for crocodile and alligator eggs, he added, though that's much more likely on the mainland than in the Florida Keys.

The problem wasn't caused by transporting the eggs, said Hord, who explained that he and the FWC have collected hundreds of thousands of alligator eggs over the past four decades. Crocodile and alligator eggs require similar conditions for proper gestation, about 90 days.

"It's not uncommon with crocodilians for something to be wrong with the eggs," Hord said.

Scientists counted between 115 and 120 crocodile nests in southeast Florida and the Everglades in 2012, said Mike Cherkiss, a U.S. Geological Survey wildlife biologist and crocodile expert.

Typically, he added, most of the eggs are viable, though more than 90 percent of hatchings die before they are a year old.

Cherkiss too said lack of fertilization or a reproductive problem with Blue No. 9 likely doomed her eggs.

Meanwhile, a group of Lower Keys neighbors will hold a "vigil" for the late, large reptile at 6 p.m. Sunday at the Port Antigua subdivision beach.

The group is "outraged" by the shooting and working on raising money to bump up the reward, Lower Matecumbe resident Tom Barken said. The FWC's Wildlife Alert Reward Association and the Humane Society put up the $6,000 in reward money. Tipsters can remain anonymous if they wish.

"There are a lot of upset people," Barken said. "We want the responsible party arrested. There are clear protocols when you see a crocodile, which calls for a person to call FWC and have them remove it."

The American crocodile in Florida is a federally threatened species. It is against federal and state law to kill, harass, feed or posses crocodiles.

Killing an American crocodile is a third-degree felony punishable by a maximum sentence of five years in prison.

The FWC asks anyone with information regarding the crocodile's death to call 888-404-3922 or Crime Stoppers at 800-346-8477.